Model Output Discussion - 12th December Onward

[Mark Neal.]

Hi everyone, thought i'd post a chart from the NAE regarding snow/rain tomorrow at 6am. I Know it tends to overplay the chance of snow/precip from what i have learn't from people saying in the last week, but if this chart is correct alot of Northern England would see snow. Also central scotland would be in good shape.

[phil nw.]

as a matter of interest, the ecm day 10 ens mean chart for tomorrow wasnt too bad was it.

Some vortex that Blue. :o

[feb1991blizzard]

Very much agree Nick, a huge leap of faith is required to see any sort of way out of the forthcoming zonality. Some intensely low heights to the North are the ongoing story.

On what timescale? as a matter of interest when do you think the next proper pressure rise to the North will occur, or do you think that zonality will remain for the rest of the winter and if it does do you think cold zonality is possible or is it guaranteed South Westerlies for the rest of the winter?

Edited December 17, 2011 by feb1991blizzard

[bluearmy]

There`s nothing confusing about current output imo.

All the main runs and i have looked at others like the GEM etc.too say the same really.

In this zonal pattern the only variables will be minor such as the exact placement of the surface features,but the overall pattern has been well modelled and i think we can safely look well beyond 72hrs.for a firm picture in this pattern.

At some point there will be something different i am sure but we can only analyise what is showing.

you are quite right phil. there is only one straw to clutch if you are expecting a sudden change in the post t144 range and thats events in the strat (which seem pretty well forecast out to day 10 so the models should be reflecting this already) or more likely, the behaviour of a developing arctic high. its doubtful that either will change the status quo of the p/v west of greenland and azores high placement giving rise to a fast jet as the two air masses meet within a fortnight. just to note quite a potent storm showing for new years day crossing northern england on the 12z naefs. these features have come and gone on differing runs recently but the likelihood of another deep depression crossing the uk in the next two weeks and causing problems must be quite high.

[BLAST FROM THE PAST]

There`s nothing confusing about current output imo.

All the main runs and i have looked at others like the GEM etc.too say the same really.

In this zonal pattern the only variables will be minor such as the exact placement of the surface features,but the overall pattern has been well modelled and i think we can safely look well beyond 72hrs.for a firm picture in this pattern.

At some point there will be something different i am sure but we can only analyise what is showing.

I am sure you are not suggesting anyone has forecasted 6 weeks of Swesterlys.

Reading between the lines i think you are looking at a change sooner.

As much as i like reading your views it would be great if you could comment by referring to the Models in this thread mate.

It really doesn`t add anything if you just say what you believe is going to develop without some data.

I

Yes some expect such a pattern until mid Jan at least, maybe even Feb. Ok Phil, maybe you can help me. I can't post links for some reason on here, my screen goes 'grey' preventing me from doing so...you or anyone know why?

regards

Edited December 17, 2011 by phil n.warks.
Removed off topic comment.

[phil nw.]

Yes some expect such a pattern until mid Jan at least, maybe even Feb. Ok Phil, maybe you can help me. I can't post links for some reason on here, my screen goes 'grey' preventing me from doing so...you or anyone know why?

regards

BFTP

I can`t help re.posting links Fred but you try PM ing Paul or one of the other Site admins to see if it`s a fault with your settings or something.

You are always welcome to comment in here to talk about the current models and state your views-if you can`t post links just state which run and time frame you are discussing,others can then view the charts.

[BLAST FROM THE PAST]

I can`t help re.posting links Fred but you try PM ing Paul or one of the other Site admins to see if it`s a fault with your settings or something.

You are always welcome to comment in here to talk about the current models and state your views-if you can`t post links just state which run and time frame you are discussing,others can then view the charts.

Thank you I'll PM them, I try normally to refer...was just being a TAD facitious earlier....apologies.

Someone posted 12z NH UKMO earlier, Gav I think. That won't end up like GFS. Massive HP over northern Russia with hints of a NW/SE axis developing?

BFTP

[phil nw.]

Thank you I'll PM them, I try normally to refer...was just being a TAD facitious earlier....apologies.

Someone posted 12z NH UKMO earlier, Gav I think. That won't end up like GFS. Massive HP over northern Russia with hints of a NW/SE axis developing?

BFTP

No probs. Fred-just like to see good posting and friendly.

Current output doesn`t suggest anything other than a westerly driven pattern but who knows down the line....

Edited December 17, 2011 by phil n.warks.

[Mark Neal.]

GFS 12z is showing that tomorrows projected streamer heading down through the midlands and into the home counties at 12pm.

[BLAST FROM THE PAST]

No probs. Fred-just like to see good posting and friendly.

Current output doesn`t suggest anything other than a westerly driven pattern but who knows down the line....

Agreed, nothing other than general westerly for rest of 2011. That I agree is likely pattern....will be interesting to see if a firm NW/SE axis comes into focus around New Year, early Jan period.

I'm still interested in a stormy time around Boxing Day though.

BFTP

Edited December 17, 2011 by BLAST FROM THE PAST

[Great Plum]

Looks like only two or 3 days of double digit maxima in the south east...

http://www.wetterzentrale.de/pics/Rtavn9617.png

http://www.wetterzentrale.de/pics/Rtavn12017.png

http://www.wetterzentrale.de/pics/Rtavn14417.png

Oh ok then, add another!

http://www.wetterzentrale.de/pics/Rtavn16817.png

[OldMetMan]

Not much change in today's model output but 2 things today get my atttention. First, as I mentioned, yesterday, intense cold building over Central asia with the corresponding very high pressure and second, correct me anyone if I am wrong, but the Canadian cold pool seems more intense and further south than normal.

Many here are looking for a more amplified pattern, as the models persist in zonality but the 2 features I mentioned above suggest that such amplification will occur in the not too distant future. Very strong baroclinicity exists off the Canadian seaboard, so it is entirely possible that an emerging LP wil deepen drastically and distort the upper flow significantly. Also, there is still what I consider remarkably high thickness values pushing up from the sub-tropics, adding I think to this possibility.

I am surprised at the way the models warm out the intense Asian cold so quickly so I am inclined to think that it may be more persistent - much depends I think on the intensity of LP running to the north of it and pulling in warmer air.

If an intense LP forms off Canada, then we can expect a strong mid-atlantic ridge, with an amplified upper cold trough in our vicinity.

I think it worth mentioning again that historically changes from mildish zonality to cold meridionality have often occurred suddenly, check out what happened in late December 1962, for example. Others are more qualified than I to explain this phenomenon, personally I believe it has to do with setting up a stable, and thus slow-changing, upper flow pattern but why such patterns exist sometimes is beyond my technical knowledge.

I think as far as the models go, even less faith than usual can be put in the GFS beyond 4-5 days, but the ECM and UKMet would likely pick up on such a switch.

[SLEETY]

Truly awful gfs 00z run.

Nearly 3 months of virtually the same pattern of the Azores or Euro Trash high preventing any real cold weather for the uk.And still no sign of a change.

Until we lose the hights to the South nothing is going to change

[Cecil Hogmanay Melchett]

Crikey the model output really goes from bad to worse with a really extended period of tripe starting tomorrow.

ECM is horrid with the azroes high ridging into Europe and a really really strong PV in tandem with a conveyor lp's across the Atlantic.

Better make the most of today after overnight blizzard left a good 2 to 3 inches .

[ICETAB]

Crikey the model output really goes from bad to worse with a really extended period of tripe starting tomorrow.

ECM is horrid with the azroes high ridging into Europe and a really really strong PV in tandem with a conveyor lp's across the Atlantic.

Better make the most of today after overnight blizzard left a good 2 to 3 inches .

The northern hemisphere view for the 240 ECM looks a little more promising to me. High pressure building of the arctic. Could that ridge forming migrate further north and split the vortex?

[bluearmy]

weird how we get moans about the upcoming pattern when there is ice/snow outside, and it seems more of the same pattern to come. given all the background signals etc, we should be looking at a (well) above average cet month. that is not what we have. the pattern looks to be similar as we head through the final third of the month. maybe the warm sectors appear to be a bit more robust than we have seen - however, there is no guarantee that they will be (this week apart). the arctic high on ecm at day 10 looks a little more of a player than it did yesterday re its ability to survive - the p/v seems intense but well spread around the NH. i see no reason to think we wont have some outbreaks of cold as we head through jan/feb. the pattern wont stay the same forever - we will have an anticyclonic phase at some point. no idea where thats going to be centred. a period of mobility was inevitable after such a long period of inactivity. the set up of p/v ne canada and azores high pumping up the high 850's is going to be difficult to shift - we've seen that plenty of time in years past. however, its usually late jan or feb when we are waiting for a change rather than december. loads of winter left and at a time when SST's will be cooler for when the change comes.

[nick sussex]

The northern hemisphere view for the 240 ECM looks a little more promising to me. High pressure building of the arctic. Could that ridge forming migrate further north and split the vortex?

The problem remains that PV limpeted in eastern Canada, until that moves away from there then the jet is going to be too strong to allow anything other than brief PM incursions.

We'll just have to see whether the models can develop a bit more amplification, in terms of todays forecast for the stratosphere another attempt at a warming at the 10Hpa level.

http://wekuw.met.fu-berlin.de/~Aktuell/strat-www/wdiag/figs/ecmwf1/temps.gif

Unfortunately nothing of much interest at the more important 30HPa level but you have to start somewhere!

I'm sure Chiono will update the strat thread once he's had his early morning espresso!

[Timmytour]

It wouldn't surprise me on current form if the low that the GFS is showing coming through between Iceland and Scotland for later this week is much closer to the southern coast of the UK! Won't make for anything particularly cold over Christmas, down south anyway, but might disrupt the predominatly mild to very mild outlook.

[snowblizzard]

Sadly, the deplorable model output continues for coldies! This pattern type seems to have been entrenched for so long. I suppose the law of averages should mean that some sort of change is due quite soon. Perhaps that's wishful thinking because the output and most upstream signals show no significant pattern change during the next 2-3 weeks! At that point we will be almost half way through our real 'winter' months, so time is rapidly running out. We were certainly spoilt last December, unfortnately I don't think we'll see anything remotely like that this winter, or at least not in the South of the country.

[Robbie Garrett]

Most certainly not. I believe that if this month ends up being slightly below average, and the same goes for January and February then we'd have a 4th consevutive winter with Below the average temperatures.

And look at the facts and opinions of some experts, the stratosphere going to warm up and the polar vortex is going to weaken so we should see something quite a bit more colder later in the winter.

I wouldn't bother looking at April onwards. I only look up to 2 months, at this range it is reasonably reliable.

February still has a chance to come below average but I'd want to see this starting to show soon on the CFS charts.

Karyo

Nothing compared to 08/09 - 09/10 -10/11 though. Hopefully that happens, as this weather pattern we have at the moment is about as boring as watching paint dry, and that's boring. I think if the weather pattern changes it will be very quick, and models wont pick up on it till lastminute.com!

There only facts and opinions though, and we can't always believe what someone says, we all know that.

karyo, a good April = a poor JJA (Summer) generally! So I hope April is about as wet as the North Atlantic, so we can get a decent summer for once where the sun is strongest.

[BurwellWeatherWatch]

We were certainly spoilt last December, unfortnately I don't think we'll see anything remotely like that this winter, or at least not in the South of the country.

Indeed would be unlikely to get the same 1 in 100 year event twice in consecutive years.

so time is rapidly running out.

not really - still 73 days of winter left and even then there are plenty of opportunities for interesting wintry weather after that.

Models certainly pretty unanimous about a milder period this week, but will be interesting to see if its 'window of opportunity' starts to narrow down as we move into the week. This is what used to happen to cold weather in the modern Christmas, but now seems to happen more to mild weather, even when the teleconnections are suggesting otherwise. Christmas itself almost certain to be snowless - at least in much of UK - but still quite plausible to see something more seasonal emerging depending where the HP decides to plonk itself down.

[bluearmy]

Not much change in today's model output but 2 things today get my atttention. First, as I mentioned, yesterday, intense cold building over Central asia with the corresponding very high pressure and second, correct me anyone if I am wrong, but the Canadian cold pool seems more intense and further south than normal.

Many here are looking for a more amplified pattern, as the models persist in zonality but the 2 features I mentioned above suggest that such amplification will occur in the not too distant future. Very strong baroclinicity exists off the Canadian seaboard, so it is entirely possible that an emerging LP wil deepen drastically and distort the upper flow significantly. Also, there is still what I consider remarkably high thickness values pushing up from the sub-tropics, adding I think to this possibility.

I am surprised at the way the models warm out the intense Asian cold so quickly so I am inclined to think that it may be more persistent - much depends I think on the intensity of LP running to the north of it and pulling in warmer air.

If an intense LP forms off Canada, then we can expect a strong mid-atlantic ridge, with an amplified upper cold trough in our vicinity.

I think it worth mentioning again that historically changes from mildish zonality to cold meridionality have often occurred suddenly, check out what happened in late December 1962, for example. Others are more qualified than I to explain this phenomenon, personally I believe it has to do with setting up a stable, and thus slow-changing, upper flow pattern but why such patterns exist sometimes is beyond my technical knowledge.

I think as far as the models go, even less faith than usual can be put in the GFS beyond 4-5 days, but the ECM and UKMet would likely pick up on such a switch.

the spreads on the naefs show a fair sized mid atlantic ridge around the 29th OMM. ecm also seems to be building a block on its spreads day 10, closer to uk. i suspect the ops will soon begin to pick up on this and the rollercoaster will begin again !!

[OldMetMan]

The problem remains that PV limpeted in eastern Canada, until that moves away from there then the jet is going to be too strong to allow anything other than brief PM incursions.

Nick, I don't think that is necessarily so. The state of the stratosphere notwithstanding, if you refer to the 2 coldest winters in the last 100 years, 1963 and 1947, you will see that the Canadian cold vortex was indeed strong on both run-ups to the intense cold.Back then, on both occasions a strong upper ridge was pushed N to the W and NW of the UK, in response to a deep LP over and to the E of the Canadian vortex, allowing downstream troughing, and corresponding influx of cold air over W Europe.

I agree the jet is very strong but as I suggested last night, it is quite possible for an intense, and more slow-moving LP to form to the E of Canada. Of course, there is the upstream pattern from that to consider, but I still think it might happen - not just yet but maybe after Christmas.

[shedhead]

I think even Alistair Campbell in his pomp would have struggled to spin the current outputs, they are woeful for cold, simple as that. As Nick said, until we can get the PV away from it's current position it's hard to see how we are going to break the zonal pattern, indeed with cold air flooding into the Western Atlantic we may see yet more deep depressions bowling towards us. The main difference however is the Jet looks set to tilt more SW-NE, meaning relatively mild not cold zonality for the north and probably more in the way of dry weather for the south. In my opinion any cold pattern looks a very long way away as things currently stand.

Edited December 18, 2011 by shedhead

[nick sussex]

Nick, I don't think that is necessarily so. The state of the stratosphere notwithstanding, if you refer to the 2 coldest winters in the last 100 years, 1963 and 1947, you will see that the Canadian cold vortex was indeed strong on both run-ups to the intense cold.Back then, on both occasions a strong upper ridge was pushed N to the W and NW of the UK, in response to a deep LP over and to the E of the Canadian vortex, allowing downstream troughing, and corresponding influx of cold air over W Europe.

I agree the jet is very strong but as I suggested last night, it is quite possible for an intense, and more slow-moving LP to form to the E of Canada. Of course, there is the upstream pattern from that to consider, but I still think it might happen - not just yet but maybe after Christmas.

Yes you can still get cold with a strong PV but further to the west especially near Baffin, indeed we've seen some easterlies with a strong PV on the western side of Greenland but in terms of being able to tap into at least some Arctic air we'd need that troughing to amplify over the eastern USA to allow for your ridge to get pulled further north.

We'll have to see what the models do with that weakish rise in pressure near the Arctic, often commented on by NOAA is the lack of observational data for that region, at least the stratosphere is moving in the right direction although its taking its time.

Edited December 18, 2011 by nick sussex